Shortwave radiative forcing of clouds and aerosols over China from 1998 to 2002

Abstract

Radiative forcing of clouds and aerosols are of research highlight in climate change science. In this paper, the shortwave radiative forcing of clouds and aerosols were estimated from Geostationary Meteorological Satellite (GMS) 5 data over China from 1998 to 2002, respectively. Such estimation is performed by a newly retrieval strategy based on radiative transfer model, which calculates shortwave cloud radiative forcing as the difference between downward solar radiation under all-sky and clear-sky, and shortwave aerosol direct radiative forcing as the difference between downward solar radiation under cloud-free sky with and without aerosol. Both instantaneous radiative forcing of cloud and aerosol were integrated to their daily mean radiative forcing, and then their annual spatial distribution can be derived. Based on them, this paper demonstrates changing patterns and processes of cloud and aerosol shortwave radiative forcing over China during those 5 years, analyses the role of cloud and aerosol that plays within each duration when downward solar radiation at surface changes. The analysis of overall radiative forcing of clouds and aerosols suggests that aerosol shortwave radiative forcing has increased by 32.8% (7.27W m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> ) and cloud shortwave radiative forcing has decreased by 7% (4.81W m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> ) for those 5 years. The impact of variability of aerosol shortwave radiative forcing has exceeded that of cloud shortwave radiative forcing, which led to the overall shortwave radiative forcing increased, thereby further decreased the downward solar radiation over China.